Cardanol based dimers and uses therefor

ABSTRACT

Cardanol based dimers are provided. The cardanol dimers are formed by hydrosylylation with silanes. Cardanol based dimers may be further reacted to form epoxy curing agents and epoxies which can be used as anti-fouling coatings on ship hulls and marine structures. The cardanol dimers may also be used to produce friction particles or phenolic resins. Methods of synthesizing the cardanol based dimers, the epoxy curing agents and the epoxies are also provided.

The present application is a divisional application under 35 U.S.C. §121from U.S. application Ser. No. 12/114,333 filed on May 2, 2008, now U.S.Pat. No. 7,858,725 which claims the benefit under 35 U.S.C. §119 of U.S.Provisional Application No. 60/927,420 filed on May 3, 2007, the entirecontents of each of which are hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention relates, in one aspect, to dimers of cardanolformed by hydrosilylation. In another aspect, the present inventionrelates to the process for producing the dimers of cardanol andderivatives of those dimers. In yet another aspect, the inventionrelates to use of cardanol dimers to produce a self-polishinganti-fouling coating for use in marine environments.

BACKGROUND

As described in U.S. Pat. No. 6,229,054, cardanol is a meta-substitutedphenol obtained by treating cashew nut shell liquid (CNSL). CNSLconsists primarily of anacardic acid which is decarboxylated whenheated, yielding cardanol. As shown in FIG. 1, cardanol is a phenol witha meta-substituted 15 carbon unsaturated aliphatic side chain. Thealiphatic side chain may have either one, two or three carbon doublebonds. Cardanol has been used as a base material to form, for example,hydroxyalkylated cardanol used as a modifier in coatings, adhesives,sealants, rubbers, plastics, elastomers and inks.

Fouling of ship bottoms and other marine structures by organisms such asbarnacles, tube worms and algae is a problem which has existed fromancient times to the present. It has become routine practice to preventthese organisms from attaching to ship bottoms and other marinestructures by coating exposed surfaces with an anti-fouling coating orpaint.

Beginning in the mid-1800's, toxicants were included in paints for shipbottoms and other marine structures. Copper compounds, such as coppersulfate and cuprous oxide, were among the first toxicants used inanti-fouling paints. Over the years, a variety of toxicants have beenused, including tin, arsenic, mercury and oxides of zinc, lead andmercury. More recently, organotins such as tributyltins, have been usedin anti-fouling marine paints.

Prevention of fouling by use of toxic paints requires maintaining alethal concentration of the toxicant in the water immediately adjacentto the surface being protected. There are at least two disadvantages tothis approach: (1) the leaching action of the toxicant from the paintwill eventually exhaust the supply of the toxicant and the paint will nolonger be effective, and (2) the toxicants are environmentallyundesirable and can be a major source of pollution in busy harbors andwaterways.

One solution to these problems has been the development of so-calledfoulant release coatings. These coatings are often silicone basedmaterials to which foulant organisms do not adhere. One disadvantage ofthese coatings is that it can be likewise difficult to adhere thematerial to the surface being protected. While this can sometimes beaddressed in part by more extensive preparation procedures, this canincrease the time and expense involved in coating a surface.

Another approach which is intended to address, at least in part, theproblem of adherence of the coating to the surface is described in U.S.Pat. No. 5,593,732. This patent describes an anti-fouling coating systemcomprised of two layers. A solid bonding layer is bonded to thesubstrate, and a solid release layer is bonded to the bonding layer.This system requires multiple components and the application of twolayers, increasing the time and expense associated with application ofthe coating.

Accordingly, there is a need for an improved anti-fouling coating whichcan be applied to marine structures, such as ship bottoms, economically,and that prevents marine organisms from bonding to the surface of themarine structure.

SUMMARY OF THE INVENTION

The present invention relates to dimers of cardanol formed byhydrosilylation of cardanol and processes for producing the cardanoldimers. In one embodiment, the cardanol dimers are produced by combiningcardanol with tetramethyldisiloxane to produce cardanol silane dimers.In another embodiment, long chain silicone cardanol dimers are producedby combining cardanol with long chain organosilanes. In yet anotherembodiments, the cardanol silane dimers are further reacted with silanesto add additional silane groups on the cardanol silane dimers.

The cardanol dimers may be crosslinked by a polysilane having anydesired number of silane units. Additional functional groups may also bebonded to the cardanol dimers to produce dimers having selectedproperties.

The present invention also relates to the use of the cardanol silanedimers to produce improved anti-fouling coatings and to methods forsynthesizing the improved anti-fouling coatings. The anti-foulingcoating is an epoxy-type coating. The epoxy agent and curing agents forthe anti-fouling coating are produced by further processing the cardanoldimers. The resulting epoxy coating is a two component system comprisingan epoxy functional resin and an amine functional curing agent bothcontaining silicone groups.

The anti-fouling coating of the present invention exhibits a low surfaceenergy and low coefficient of friction. The coating may be applied bybrush or spray application and has excellent adhesion to metal. Standardpaint pigments and extenders can be added to the coating. The epoxy hasan acceptable potlife. When applied to an exposed surface such as a boathull, the coating resists marine fouling without the use of any toxiccomponents.

The cardanol dimers of the present invention may also be used to producefriction particles or in phenolic resins where phenol is used in anelectrophilic addition reaction. Friction particles formed from thecardanol dimers of the present invention exhibit lower weight loss withheating by thermogravimetric analysis, have improved heat resistance andexhibit improved thermal shock properties.

Other advantages of the coating will be apparent to those skilled in theart based upon the following detailed description of preferredembodiments.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a structural diagram of cardanol.

FIGS. 2A and 2B are schematics showing a process for synthesis of acardanol silane dimer from cardanol.

FIG. 3 is a schematic showing a process for synthesis of a cardanolsilane dimer having an enhanced silane content.

FIG. 4 is a schematic showing a process for synthesis of a cardanolsilane dimer having a fluorinated silane.

FIG. 5 is a schematic showing a process for synthesis of a curing agentfor the anti-fouling coating from the cardanol silane dimer.

FIG. 6 is a schematic showing a process for synthesis of a curing agentfor the anti-fouling coating from the cardanol silane dimer having anenhanced silane content.

FIG. 7 is a schematic showing a process for synthesis of a curing agentfor the anti-fouling coating from the cardanol silane dimer having afluorinated silane.

FIG. 8 is a schematic showing a process for synthesis of a curing agentfrom cardanol and an aminopropylsiloxane.

FIGS. 9A and 9B are schematics showing a process for synthesis of acuring agent from a cardanol having a fluorinated silane and anaminopropylsiloxane.

FIGS. 10A and 10B are schematics showing a process for synthesis of acuring agent from a cardanol having a silane group and anaminopropylsiloxane.

FIG. 11 is a schematic showing a process for synthesis of an epoxy resinfrom a cardanol silane dimer and epichlorohydrin.

FIG. 12 is a schematic showing a process for synthesis of an epoxy resinfrom a cardanol silane dimer having an enhanced silane content andepicholorohydrin.

FIG. 13 is a schematic showing a process for synthesis of an epoxy resinfrom a cardanol silane dimer having a fluorinated silane andepichlorohydrin.

FIGS. 14A and 14B are schematics showing a process for the synthesis ofa long chain silicone cardanol dimer.

FIG. 15 is a schematic showing a process for the synthesis of an epoxyresin from a long chain silicone cardanol dimer.

FIG. 16 is a schematic showing a process for the synthesis of a curingagent from a long chain silicone dimer.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention relates to dimers of cardanol, processes forproducing dimers of cardanol, and use of the dimers of cardanol infriction particles or in epoxy coatings that may be used, for example,as anti-fouling coatings on ships or marine structures. As described inU.S. Pat. No. 6,229,054, cardanol is obtained by treating cashew nutshell liquid (CNSL). CNSL consists primarily of anacardic acid which isdecarboxylated when heated, yielding cardanol. As shown in FIG. 1,cardanol is a phenol with a meta-substituted 15 carbon unsaturatedaliphatic side chain. The aliphatic side chain may have either one, twoor three carbon double bonds. In preferred embodiments of the presentinvention, the unsaturated aliphatic side chain is pentadeca-8,11-diene.

The cardanol dimers of the present invention are synthesized bycross-linking the aliphatic side chains on the cardanol. In someembodiments, the aliphatic side chains are cross-linked using amultifunctional silicon molecule, such as for example a siloxane or apolysiloxane. In one embodiment, the cardanol dimers generally have theformula:

In this embodiment, z may be any desired number to obtain a cardanoldimer having the desired properties. In preferred embodiments, z isbetween 1 and 200, and in an especially preferred embodiment, z is 1. Xand y may be the same or different species, and they may be any speciesthat imparts desired properties on the resulting dimer. In preferredembodiments, x and y are selected from hydrogen, a halide, a hydroxylgroup, a saturated or unsaturated, branched or unbranched aliphaticcarbon group having between 1 and 100 carbon atoms, an aromatic carbongroup, or a silane or polysilane group. The aliphatic carbon group mayalso be substituted at one or more carbon atoms with a hydroxyl group, ahalide or any other atom or radical that can be bonded to carbon. Itshould be understood that, as explained for the embodiment of the dimerdescribed below, it is not necessary to have any substitution at the C₈location, and in that case the double bond between the eighth and ninthcarbons on the meta-substituted side chain on the cardanol molecule isnot reduced.

Alternatively, the cardanol dimer may be crosslinked at two locations onthe meta-substituted side chain. In this embodiment, at the C₉ locationon the meta-substituted side chain, a second silane or polysilanecrosslink is formed to produce the following dimer:

The cardanol dimers of the present invention have numerous uses. Forexample, the cardanol dimers may be used as a substitute for bis-phenylmolecules in applications where the cardanol dimers provide desirableproperties, or the cardanol dimers may be used to form frictionparticles. As described below, the cardanol dimers may also be used toprepare epoxies and curing agents used, for example, in coatings.

In a preferred embodiment of the invention, z is 1, and there is nosubstitution at the C₉ location on the aliphatic side chain on thecardanol. The resulting dimer has the following structure:

The resulting cardanol dimers of this embodiment may be further modifiedas described in detail below to include additional silane orfluorosilane groups bound to the aliphatic side chains on the cardanoldimers. These cardanol dimers may be used, for example, as raw materialsto produce epoxies and curing agents used in epoxy coatings, such ascoatings having improved anti-fouling properties for use in marinevessels.

In another embodiment of the invention, a long chain silicone cardanoldimer is formed by joining two cardanol molecules by a silicone basedpolymer. In one embodiment, the silicone based polymer is apolydimethylsiloxane of the formula:

Where n=5-200. The resulting cardanol dimers are shown in FIG. 14. Thesecardanol dimers may be used to form epoxy resins or curing agents asdescribed in detail below.

The following descriptions of preferred processes for producing thecardanol dimers and products formulated using the cardanol dimers areintended as examples only and are not intended to limit the full scopeof the invention described and claimed.

As shown in FIGS. 2A and 2B, in one embodiment of the invention,cardanol (1) is combined with acetic anhydride ((CH₃CO)₂O) (2), in anappropriate reactor and mixed at a temperature of between about 120° C.to 125° C. for between about 3 and 4 hours. In a preferred embodiment,the cardanol (1) and the acetic anhydride (2) are mixed at a temperatureof about 125° C. for a period of about 4 hours. The reactor ispreferably equipped with a mechanical agitation device to mix thereactants and a temperature control mechanism, such as a thermocoupledevice, to control the temperature in the reactor. An excess of aceticanhydride is provided to obtain maximum reaction of the cardanol. In oneembodiment, the mole ratio of cardanol to acetic anhydride is 1:1.23. Asshown in FIGS. 2A and 2B, the cardanol and acetic anhydride react andthe hydroxyl group on the benzene ring of the cardanol molecule isreplaced by an acetate group to form 3-(pentadecyl)-phenyl acetate,referred to herein as “acetate substituted cardanol” (3).

As further shown in FIGS. 2A and 2B, the acetate substituted cardanol(3) is combined with tetramethyldisiloxane (TMDS) (4) in an appropriatereactor in the presence of a catalyst to form an acetate substitutedcardanol silane dimer (5). The reactor is preferably equipped with amechanical agitation device to mix the reactants. A thermocoupletemperature control mechanism may be used to control the temperature inthe reactor. The acetate substituted cardanol is provided in excess ofthe stoichiometric amount to obtain maximum reaction with the TMDS. Inone embodiment, the mole ratio of TMDS to acetate substituted cardanolis 1:6.

Any appropriate catalyst known to those skilled in the art may be usedto catalyze the reaction. In particular, platinum containing catalyststhat may be used in hydrolization reactions can be used to catalyze thereaction. For example, any of the following catalysts may be used:H₂PtO₄6H₂O; PtO₂; O[Si(CH₃)₂CH═CH₂]₂Pt; Pt[(VMe₂Si)₂O][ViMe₂SiOSiM]. Ina preferred embodiment, the catalyst is chloroplatinic acid(H₂PtCl₆6H₂O). The reactor is maintained at a temperature of betweenabout 120° C. to about 160° C. for a period of about 20 hours. As shownin FIG. 2, acetate substituted cardanol silane dimers (5) are formed bycross-linking acetate substituted cardanol molecules with the TMDS. Thedouble bond between C₁₁ and C₁₂ on the pentadeca-8,11-diene portion oftwo cardanol molecules are reduced and Si—C bonds are formed between thepentadeca-8,11-diene and the TMDS. The acetate substituted cardanolsilane dimer thus formed is then hydrolized with acid to remove theacetate group on the benzene ring of the cardanol and substitute ahydroxyl group to form a cardanol silane dimer (6). The hydrolizationstep can be performed using, for example, sulfuric acid or, preferably,hydrochloric acid. The acid wash step is preferably performed at atemperature of about 80° C. and at a pH of about 0.6.

The cardanol silane dimer formed by the process described above has aviscosity at 25° C. of approximately 150 cP, an iodine number of 125,and a dimer % by weight of about 95.3. As described below, the resultingcardanol silane dimers may be further processed to bond further silanegroups to the cardanol silane dimer.

As shown in FIG. 3, the acetate substituted cardanol silane dimer (5)formed by the process described above may be combined withdimethyldimethoxysilane (DMDMOS) (7) in a reactor in the presence of acatalyst. In particular, platinum containing catalysts that may be usedin hydrolization reactions can be used to catalyze the reaction. Forexample, any of the following catalysts may be used: H₂PtO₄6H₂O; PtO₂;O[Si(CH₃)₂CH═CH₂]₂Pt; Pt[(VMe₂Si)₂O][ViMe₂SiOSiM]. In a preferredembodiment, the catalyst is chloroplatinic acid (H₂PtCl₆6H₂O). Aftercombining the reactants and the catalyst in the reactor, the temperatureis maintained between about 120° C. and 160° C. for a period of about 20hours. The reactor is preferably equipped with a mechanical agitationdevice to mix the reactants and a temperature control mechanism, such asa thermocouple device, to control the temperature in the reactor. Anexcess of DMDMOS is provided to obtain maximum reaction with thecardanol silane dimers. In one embodiment, the mole ratio of cardanolsilane dimer to DMDMOS is 1:4.

The acetate substituted cardanol silane dimer and the DMDMOS react toform an acetate substituted cardanol silane dimer having additionalsilane groups at the C₉ location on the pentadeca-8,11-diene portion ofthe cardanol (8). The resulting acetate substituted cardanol silanedimer is then hydrolyzed with acid to remove the acetate group from thebenzene ring and substitute a hydroxyl group to form a cardanol silanedimer having additional silane groups (9). The hydrolyzation step can beperformed using, for example, sulfuric acid or, preferably, hydrochloricacid. The hydrolyzation step is preferably performed at a temperature ofabout 80° C. and at a pH of about 0.6.

In another embodiment of the present invention, fluoronated silanegroups may be substituted on the cardanol silane dimer. As shown in FIG.4, the acetate substituted cardanol silane dimer (5) formed by theprocess described above may be combined with (tridecafluoro-1, 1, 2, 2tetrahydrooctyl)silane (10) in the presence of a catalyst. Inparticular, platinum containing catalysts that may be used inhydrolization reactions can be used to catalyze the reaction. Forexample, any of the following catalysts may be used: H₂PtO₄6H₂O; PtO₂;O[Si(CH₃)₂CH═CH₂]₂Pt; Pt[(VMe₂Si)₂O][ViMe₂SiOSiM]. In a preferredembodiment, the catalyst is chloroplatinic acid (H₂PtCl₆6H₂O). Aftercombining the reactants and the catalyst in the reactor, the temperatureis maintained between about 120° C. and 160° C. for a period of about 20hours. The reactor is preferably equipped with a mechanical agitationdevice to mix the reactants and a temperature control mechanism, such asa thermocouple device, to control the temperature in the reactor. Anexcess of (tridecafluoro-1,1,2,2 tetrahydrooctyl)silane is provided toobtain maximum reaction with the cardanol silane dimers. In oneembodiment, the mole ratio of cardanol silane dimer to(tridecafluoro-1,1,2,2 tetrahydrooctyl)silane is 1:4.

The acetate substituted cardanol silane dimer (5) and the(tridecafluoro-1,1,2,2 tetrahydrooctyl)silane (10) react to form anacetate substituted cardanol silane dimer having (tridecafluoro-1,1,2,2tetrahydrooctyl)silane groups at the C₉ location on the meta-substitutedaliphatic carbon portion of the cardanol (11). The resulting acetatesubstituted cardanol silane dimer is then hydrolyzed with acid to removethe acetate group from the benzene ring and substitute a hydroxyl groupto form a cardanol silane dimer having (tridecafluoro-1,1,2,2tetrahydrooctyl)silane groups (12). The hydrolyzation step can beperformed using, for example, sulfuric acid or, preferably, hydrochloricacid. The hydrolization step is preferably performed at a temperature ofabout 80° C. and at a pH of about 0.6.

One of the uses of the cardanol silane dimers described above is incuring agents and epoxy components that may be used in anti-foulingcoatings for ships hulls or marine structures. The cardanol silanedimers prevent foulants form adhering to the hull or marine structureand thereby prevent fouling of the structure.

As shown in FIG. 5, in one embodiment, a curing agent for an epoxy maybe synthesized by combining the cardanol silane dimer (6) produced asdescribed above with paraformaldehyde (13) and an amine in a Mannichreaction. In the shown in FIG. 5, the amine is dimethylaminopropylamine(14). The reactants may be combined in any appropriate reactor withagitation and a temperature control mechanism, such as, for example, athermocouple device. The reactants are mixed at a temperature of betweenabout 70° C. to about 80° C. for a period of about 4 to about 6 hours.The paraformaldehyde and the dimethylaminopropylamine are provided inexcess relative to the cardanol silane dimer. In one embodiment the moleratio of dimer to paraformaldehyde to dimethylaminopropylamine is1:2.4:2.4.

The paraformaldehyde (13) and dimethylaminopropylamine (14) react withthe cardanol silane dimer (6) to form a dimethylaminopropylaminomethylcardanol silane dimer curing agent (15). The resulting curing agent hasa viscosity at 25° C. of about 70,300 cP, an amine value of 186 and agel time of 48.7.

As shown in FIG. 6, in another embodiment, the curing agent componentmay be synthesized by combining the silane substituted cardanol silanedimer (9) produced as described above with paraformaldehyde (13) and anamine in a Mannich reaction. In the embodiment shown in FIG. 6, theamine is dimethylaminopropylamine (14). The reactants may be combined inany appropriate reactor with agitation and a temperature controlmechanism, such as, for example, a thermocouple device. The reactantsare mixed at a temperature of between about 70° C. to about 80° C. for aperiod of about 4 to about 6 hours. The paraformaldehyde and thedimethylaminopropylamine are provided in excess relative to the silanesubstituted cardanol silane dimer. In one embodiment the mole ratio ofdimer to paraformaldehyde to dimethylaminopropylamine is 1:2.4:2.4. Theparaformaldehyde (13) and dimethylaminopropylamine (14) react with thesilane substituted cardanol silane dimer (6) to form adimethylaminopropylaminomethyl silane substituted cardanol silane dimercuring agent (16).

As shown in FIG. 7, in yet another embodiment, the curing agentcomponent may be synthesized by combining the fluorosilane cardanolsilane dimer (12) produced as described above with paraformaldehyde (13)and an amine in a Mannich reaction. In the embodiment shown in FIG. 7,the amine is dimethylaminopropylamine (14). The reactants may becombined in any appropriate reactor with agitation and a temperaturecontrol mechanism, such as, for example, a thermocouple device. Thereactants are mixed at a temperature of between about 70° C. to about80° C. for a period of about 4 to about 6 hours. The paraformaldehydeand the dimethylaminopropylamine are provided in excess relative to thefluorosilane substituted cardanol silane dimer. In one embodiment themole ratio of dimer to paraformaldehyde to dimethylaminopropylamine is1:2.4:2.4. The paraformaldehyde (13) and dimethylaminopropylamine (14)react with the fluorosilane cardanol silane dimer (12) to form afluorosilane dimethylaminopropylaminomethyl cardanol silane dimer curingagent (17).

In another embodiment, the curing agent is synthesized from cardanol and1,3-Bis (3-aminopropyl) polydimethylsiloxane. As shown in FIG. 8,cardanol (1), paraformaldehyde (13) and1,3-Bis(3-aminopropyl)polydimethylsiloxane (18) are combined in anappropriate reactor with agitation and a temperature control mechanism,such as, for example, a thermocouple device. The reactants are mixed ata temperature of between about 70° C. to about 80° C. for a period ofabout 4 to about 6 hours. The paraformaldehyde and the1,3-Bis(3-aminopropyl)polydimethylsiloxane are provided in excessrelative to the cardanol. In a preferred embodiment the mole ratio ofcardanol to paraformaldehyde to dimethylaminopropylamine is 1:1.2:1.2.In preferred embodiments, the 1,3-Bis(3-aminopropyl)polydimethylsiloxanehas 9, 13, 33 or 66 dimethylsiloxane units. The1,3-Bis(3-aminopropyl)polydimethylsiloxane bonds to the cardanol at theC₅ position on the phenol portion of the cardanol to form the1,3-Bis(3-aminopropyl)polydimethylsiloxane modified cardanol (19) curingagent.

In another embodiment, a fluorosilane modified cardanol based curingagent is synthesized as shown in FIGS. 9A and 9B. Cardanol (1) andacetic anhydride (2) are combined in an appropriate reactor andmaintained at a temperature of about 125° C. for about four hours asdescribed above to produce an acetate substituted cardanol (3). Theacetate substituted cardanol (3) is combined in an appropriate reactorwith (tridecafluoro-1,1,2,2 tetrahydrooctyl)silane (10) in the presenceof a catalyst. In particular, platinum containing catalysts that may beused in hydrolization reactions can be used to catalyze the reaction.For example, any of the following catalysts may be used: H₂PtO₄6H₂O;PtO₂; O[Si(CH₃)₂CH═CH₂]₂Pt; Pt[(VMe₂Si)₂O][ViMe₂SiOSiM]. In a preferredembodiment, the catalyst is chloroplatinic acid (H₂PtCl₆6H₂O). Theacetate substituted cardanol and the (tridecafluoro-1,1,2,2tetrahydrooctyl)silane are provided in stoichiometric molar amounts.After combining the reactants and the catalyst in the reactor, thetemperature is maintained between about 120° C. and 160° C. for a periodof about 20 hours. As shown in FIGS. 9A and 9B, the acetate substitutedcardanol (3) and the (tridecafluoro-1,1,2,2 tetrahydrooctyl)silane (10)react to form an acetate substituted cardanol having(tridecafluoro-1,1,2,2 tetrahydrooctyl)silane groups at the C₉ and C₁₁locations on the meta-substituted aliphatic carbon portion of thecardanol (20).

The resulting acetate substituted cardanol with the(tridecafluoro-1,1,2,2 tetrahydrooctyl)silane groups (20) is hydrolyzedwith acid to remove the acetate group from the benzene ring andsubstitute a hydroxyl group to form cardanol with a(tridecafluoro-1,1,2,2 tetrahydrooctyl)silane group (21). Thehydrolization step can be performed using, for example, sulfuric acidor, preferably, hydrochloric acid. The hydrolization step is preferablyperformed at a temperature of about 80° C. and at a pH of about 0.6.

As further shown in FIGS. 9A and 9B, the cardanol with a(tridecafluoro-1,1,2,2 tetrahydrooctyl)silane group (21),paraformaldehyde (13) and 1,3-Bis(3-aminopropyl)polydimethylsiloxane(18) are combined in a reactor and mixed at a temperature of betweenabout 70° C. and about 80° C. for approximately 4 to 6 hours. Inpreferred embodiments, the 1,3-Bis(3-aminopropyl)polydimethylsiloxanehas 9, 13, 33 or 66 dimethylsiloxane units. The1,3-Bis(3-aminopropyl)polydimethylsiloxane bonds to the cardanol at theC₉ position on the phenol portion of the cardanol to form a1,3-Bis(3-aminopropyl)polydimethylsiloxane modified cardanol with a(tridecafluoro-1,1,2,2 tetrahydrooctyl)silane group (22), which can beused as a curing agent.

In yet another embodiment of the invention, a dimethyldimethoxysilanemodified cardanol based curing agent is synthesized as shown in FIGS.10A and 10B. Cardanol (1) and acetic anhydride (2) are combined in areactor and mixed at a temperature of about 125° C. for about four hoursas described above to produce an acetate substituted cardanol (3). Theacetate substituted cardanol (3) is combined withdimethyldimethoxysilane (23) in the presence of a catalyst. Inparticular, platinum containing catalysts that may be used forhydrolization reactions can be used to catalyze the reaction. Forexample, any of the following catalysts may be used: H₂PtO₄6H₂O; PtO₂;O[Si(CH₃)₂CH═CH₂]₂Pt; Pt[(VMe₂Si)₂O][ViMe₂SiOSiM]. In a preferredembodiment, the catalyst is chloroplatinic acid (H₂PtCl₆6H₂O). Aftercombining the reactants and the catalyst in the reactor, the temperatureis maintained between about 120° C. and 160° C. for a period of about 20hours. The dimethyldimethoxysilane is provided in excess relative to theacetate substituted cardanol. In one embodiment, the mole ratio ofacetate substituted cardanol to dimethyldimethoxysilane is 1:3.

The acetate substituted cardanol (3) and the dimethyldimethoxysilane(23) react to form an acetate substituted cardanol having adimethyldimethoxysilane group at the C₉ and C₁₁ locations on themeta-substituted aliphatic carbon portion of the cardanol (24). Theresulting acetate substituted cardanol with the dimethyldimethoxysilanegroups (24) is hydrolyzed with acid to remove the acetate group from thebenzene ring and substitute a hydroxyl group to form cardanol withsubstituted dimethyldimethoxysilane groups (25). The hydrolization stepcan be performed using, for example, sulfuric acid or, preferably,hydrochloric acid. The hydrolization step is preferably performed at atemperature of about 80° C. and at a pH of about 0.6.

As further shown in FIGS. 10A and 10B, the cardanol with adimethyldimethoxysilane group (25), paraformaldehyde (13) and1,3-Bis(3-aminopropyl)polydimethylsiloxane (18) are combined in areactor and mixed at a temperature of between 70° C. and 80° C. forapproximately 4-6 hours. In preferred embodiments, the1,3-Bis(3-aminopropyl)polydimethylsiloxane has 9, 13, 33 or 66dimethylsiloxane units. The 1,3-Bis(3-aminopropyl)polydimethylsiloxanebonds to the cardanol at the C₉ position on the phenol portion of thecardanol to form a 1,3-Bis(3-aminopropyl)polydimethylsiloxane modifiedcardanol with a dimethyldimethoxysilane group (26), which can be used asa curing agent.

The epoxy component of the anti-fouling coating is synthesized in anepoxidation reaction by combining any of the cardanol silane dimersdescribed above with epichlorohydrin in a caustic soda solution,preferably a 50% caustic soda solution. As shown in FIG. 11, in oneembodiment of the invention, the cardanol silane dimer (6) synthesizedby the process described above and epichlorohydrin (27) are combined ina reactor with a 50% caustic soda solution. The epichlorohydrin isprovided in excess relative to the cardanol silane dimer. In oneembodiment, the mole ratio of cardanol silane dimer to epichlorohydrinis 1:6. The reactor is maintained at a temperature of between 65° C. and70° C. for a period of approximately 3 to 4 hours. As shown in FIG. 11,the epichlorohydrin reacts with the hydroxyl groups on the benzene ringsof the cardanol silane dimers to form the cardanol silane epoxycomponent (28) of the anti-fouling coating. The epoxy component has aviscosity at 25° C. of approximately 285 cPs, an EEW of 494, a volumeloss of 2.7 and a hydrolysable Cl value of 3.6.

As shown in FIG. 12, in another embodiment of the invention, the silanesubstituted cardanol silane dimer (9) synthesized by the processdescribed above is combined with epichlorohydrin (27) in a reactor witha caustic soda solution, preferably 50% caustic soda solution. Theepichlorohydrin is provided in excess relative to the silane substitutedcardanol silane dimer. In a preferred embodiment, the mole ratio of thesilane substituted cardanol silane dimer to epichlorohydrin is 1:6. Thereactor is maintained at a temperature of between 65° C. and 70° C. fora period of approximately 3-4 hours. As shown in FIG. 12, theepichlorohydrin reacts with the hydroxyl groups on the benzene rings ofthe cardanol silane dimers to form a silane substituted cardanol silaneepoxy (29).

As shown in FIG. 13, in yet another embodiment of the invention, thecardanol silane dimer having substituted (tridecafluoro-1,1,2,2tetrahydrooctyl)silane groups (12) synthesized by the process describedabove and epichlorohydrin (27) are combined in a reactor with a causticsoda solution, preferably a 50% caustic soda solution. Theepichlorohydrin is provided in excess relative to the fluorosilanesubstituted cardanol silane dimer. In one embodiment, the mole ratio offluorosilane substituted cardanol silane dimer to epichlorohydrin is1:6. The reactor is maintained at a temperature of between 65° C. and70° C. for a period of approximately 3 to 4 hours. As shown in FIG. 13,the epichlorohydrin reacts with the hydroxyl groups on the benzene ringsof the cardanol silane dimer having (tridecafluoro-1,1,2,2tetrahydrooctyl)silane groups to form a fluorosilane substitutedcardanol silane epoxy (30).

In another embodiment of the invention shown in FIGS. 14A and 14B, along chain silicone cardanol dimer is formed. Cardanol (1) is combinedwith acetic anhydride ((CH₃CO)₂O) (2) in an appropriate reactor andmaintained at a temperature of between about 120° C. to 125° C. forbetween about 3 and 4 hours. In a preferred embodiment, the cardanol (1)and the acetic anhydride (2) are mixed at a temperature of about 120° C.for a period of about 4 hours. The reactor is preferably equipped with amechanical agitation device to mix the reactants and a temperaturecontrol mechanism, such as a thermocouple device, to control thetemperature in the reactor. An excess of acetic anhydride is provided toobtain maximum reaction of the cardanol. In one embodiment, the moleratio of cardanol to acetic anhydride is about 1:1.23. As shown in FIGS.14A and 14B, the cardanol and acetic anhydride react and the hydroxylgroup on the benzene ring of the cardanol molecule is replaced by anacetate group to form an acetate substituted cardanol (3).

As further shown in FIGS. 14A and 14B, the acetate substituted cardanol(3) is combined with a polydimethylsiloxane (31) in an appropriatereactor in the presence of a catalyst. The polydimethylsiloxanepreferably has the following formula with n between 5 and 200.

The reactor is preferably equipped with a mechanical agitation device tomix the reactants and a thermocouple temperature control mechanism tocontrol the temperature in the reactor. The cardanol (3) and thepolydimethylsiloxane (31) react to form an acetate substituted longchain silicone cardanol dimer. (32). The acetate substituted cardanol isprovided in excess of the stoichiometric amount to obtain maximumreaction with the polydimethylsiloxane (31). In one embodiment, the moleratio of polydimethylsiloxane to acetate substituted cardanol is 1:6.

Any appropriate catalyst known to those skilled in the art may be usedto catalyze the reaction. In particular, platinum containing catalyststhat may be used for hydrolization reactions can be used to catalyze thereaction. For example, any of the following catalysts may be used:H₂PtO₄6H₂O; PtO₂; O[Si(CH₃)₂CH═CH₂]₂Pt; Pt[(VMe₂Si)₂O][ViMe₂SiOSiM]; orH₂PtCl₆6H₂O. The reactor is maintained at a temperature of between about80° C. to about 100° C. for a period of about 10 hours. As shown inFIGS. 14A and 14B, acetate substituted long chain silicone cardanoldimers (32) are formed by cross-linking acetate substituted cardanolmolecules with the polydimethylsiloxane. The double bond between C₁₁ andC₁₂ on the pentadeca-8,11-diene portion of two cardanol molecules arereduced and Si—C bonds are formed between the pentadeca-8,11-diene andthe polydimethylsiloxane. The acetate substituted long chain siliconecardanol dimer thus formed is then hydrolyzed with acid to remove theacetate group on the benzene ring of the cardanol and substitute ahydroxyl group to form a long chain silicone cardanol dimer (33). Thehydrolization step can be performed using, for example, sulfuric acidor, preferably, hydrochloric acid. The hydrolization step is preferablyperformed at a temperature of about 80° C. and at a pH of about 0.6.

When n=5 on the polydimthylsiloxane, the long chain silicone cardanoldimer formed by the process described above has a viscosity at 25° C. ofapproximately 280 cP, and an iodine number of 102.

The long chain silicone cardanol dimer may be used to produce an epoxyresin component and a curing agent for a coating that may be used as ananti-fouling coating. The epoxy resin component may be synthesized in anepoxidation reaction by combining the long chain silicone cardanol dimerdescribed above with epichlorohydrin in a caustic soda solution,preferably a 50% caustic soda solution. As shown in FIG. 15, in oneembodiment of the invention, the long chain silicone cardanol dimer (33)synthesized by the process described above and epichlorohydrin (27) arecombined in a reactor with a 50% caustic soda solution. Theepichlorohydrin is provided in excess relative to the long chainsilicone cardanol dimer. In a preferred embodiment, the mole ratio oflong chain silicone cardanol dimer to epichlorohydrin is 1:6. Thereactor is maintained at a temperature of between 65° C. and 70° C. fora period of approximately 3 to 4 hours. As shown in FIG. 15, theepichlorohydrin reacts with the hydroxyl groups on the benzene rings ofthe long chain silicone cardanol dimers to form an epoxy component (34)which can be used in an anti-fouling coating.

A curing agent for an epoxy may be synthesized by combining the longchain silicone cardanol dimer (33) produced as described above withparaformaldehyde (13) and an amine in a Mannich reaction. In oneembodiment shown in FIG. 16, the amine (35) is of the form NH₂RNH₂ inwhich R is any saturated or unsaturated, branched, unbranched oraromatic carbon based radical. Examples of amines that may be used inthis embodiment include EDA, DETA, TETA, TEPA, MXDA, and DMAPA. Thereactants may be combined in any appropriate reactor with agitation anda temperature control mechanism, such as, for example, a thermocoupledevice. The reactants are mixed at a temperature of between about 70° C.to about 80° C. for a period of about 4 to about 6 hours. Theparaformaldehyde and the amine may be provided in excess relative to thelong chain silicone cardanol dimer, although in one embodiment the moleratio of dimer to paraformaldehyde to amine is about 1:1:1. Theparaformaldehyde (13) and the amine (35) react with the long chainsilicone cardanol dimer (33) to form an amine cardanol dimer curingagent (36).

The anti-fouling coating is made by mixing one or more of the epoxycomponents described above with one or more of the curing agentsdescribed above. Typically, the proportion of epoxy component to curingagent will be between about 0.6 to 1.8 amine functional equivalents toepoxy functional equivalents, preferably about 0.8 to 1.5 functionalequivalents and more preferably between about 0.9 to 1.2 functionalequivalents. In a preferred embodiment, the anti-fouling coatingcomprises the cardanol silane dimer epoxy (28) combined with thedimethylaminopropylaminomethyl cardanol silane dimer curing agent (15).In this embodiment, the proportion of the cardanol silane dimer epoxy(28) to dimethylaminopropylaminomethyl cardanol silane dimer curingagent (15) between about 51% to 49%.

After the epoxy component and the curing agent are combined, theanti-fouling coating is applied to a surface using standard methodsknown to those skilled in the art. Prior to application of theanti-fouling coating, the surface to be coated is cleaned and preparedusing standard methods known to those skilled in the art. The coatingmay be applied to the prepared surface by brush, troweling, roller orspray applicator. The coating may be applied directly to the substrateor may be part of a multicoat system to protect the marine structure.

The anti-fouling coating is typically applied to achieve a thicknessafter curing of between about 25 microns to 1000 microns, preferablybetween about 100 microns to 500 microns. Curing time will depend uponthe epoxy component and curing agent used. Typically, the curing timewill be 6 to 48 hours.

Any of the cardanol dimers described above may also be used in siliconecardanol dimer based phenolic resins or to form friction particles.Friction particles typically have a resilient nature which providescushioning in certain applications such as in brake pads and linings.Friction particles may decompose at elevated temperatures on the surfaceof a friction face, such as the surface of a brake lining, which cancontrol wear and prevent excessive temperatures from developing. Thefriction particles may be used in phenolic binder resins resins used inbrake pads. Friction particles formed using the cardanol dimersdescribed above have better performance characteristics than frictionparticles formed using other silicone based materials. The frictionparticles formed from the cardanol dimers of the present inventionexhibit reduced weight loss measured by thermogravimetric analysis,improved heat resistance and better thermal shock characteristics.

The cardanol dimers described above may also be used in phenolic resinswhere phenol is used in an electrophilic addition reaction.

The following examples are provided to provide additional description ofthe synthesis of certain embodiments of the claimed inventions. Theseare exemplary only, and are not intended to limit the invention in anyaspect.

EXAMPLE 1 Synthesis of Acetate Substituted Cardanol

Acetic anhydride and cardanol are combined in a reactor. In a laboratorysetting, the reactor is typically a glass flask. A slight excess ofacetic anhydride is used, typically about 20% more than thestoichiometric quantity. The reactor is heated to a temperature ofbetween 120° C. and 125° C. and held for three hours. If desired, theprogress of the reaction can be measured by FTIR. Absorption between3200 cm⁻¹ and 3500 cm⁻¹ represents OH absorption.

After the reaction is complete, the acetate substituted cardanol ispurified by vacuum distillation. Acetic anhydride has a boiling point of138-140° C., and acetic acid has a boiling point of 117-118° C. Both ofthese compounds are easily removed by vacuum distillation. After theunreacted acetic anhydride and the acetic acid by-product are removed,the acetate substituted cardanol is purified using vacuum distillationat a vacuum of 3 to 5 mm Hg and a temperature of between 240° C. and275° C.

EXAMPLE 2 Hydrosilylation of Acetate Substituted Cardanol

The acetate substituted cardanol of example 1 and TMDS are mixed in areactor at a mole ratio of 6:1. Speier's catalyst is added to achieve alevel of 2000 ppm based upon the quantity of TMDS used. The reactor isheated to a temperature of 70° C. and held for two hours. Thetemperature is then increased to 80° C. and held for two hours. Thetemperature is then increased again to 100° C. and held for two hours.The temperature is then raised to 120° C. and held until the TMDS is nolonger observed by FTIR. TMDS has a characteristic peak at 2120 cm⁻¹. Inone run, the reaction was complete in about 10 hours.

EXAMPLE 3 Hydrolysis of Acetate Substituted Cardanol Dimer to Produce aHigh Viscosity Dimer

The acetate group on the dimer of Example 2 is removed by hydrolysisusing HCl/H₂O. For every 500 g of acetate substituted cardanol in thereactor, the following are added: 40 g of 37.5% HCl, 80 g of deionizedwater and 80 g of isopropyl alcohol. The temperature of the reactor israised to 80° C. and held for 4 hours.

After four hours the HCl, water and isopropyl alcohol are removed byvacuum distillation of 200° C. and 5 mm Hg. The vacuum distillation iscontinued at 275° C. and 3 mm Hg to remove all free Cardanol. Thematerial remaining in the reactor is a high viscosity cardanol dimer.The viscosity of the material produced in this example was about 9200 cPat 25° C., and the material had an iodine number of about 187.

EXAMPLE 4 Hydrolysis of Acetate Substituted Cardanol Dimer to Produce aLow Viscosity Dimer

The acetate group on the dimer of Example 2 is removed by hydrolysisusing HCl/H₂O. For every 500 g of acetate substituted cardanol in thereactor, the following are added: 40 g of 37.5% HCl, 80 g of deionizedwater, and 80 g of isopropyl alcohol. The reactor is heated to 80° C.and held at that temperature for 4 hours. The contents are then allowedto cool to room temperature.

The contents of the reactor are transferred to a separation funnel andallowed to settle to separate the aqueous and organic phases. The bottomaqueous phase is drained. The organic phase is washed twice with a 15%Brine solution, and the bottom aqueous phase is drained.

Following washing, the material is returned to the flask and vacuumdistilled at 200° C. and 5 mm Hg to remove the solvent. The vacuumdistillation is continued at 270° C. and 3 mm Hg to remove freeCardanol. The remaining material is a low viscosity cardanol dimer. Thedimer has a viscosity of 280 cP at 25° C. and an iodine number of 154.

EXAMPLE 5 Synthesis of High Silicone Content (45%) Curing Agents fromthe Low and High Viscosity Dimers

The following reagents are used in the amounts shown to synthesizecuring agents from the high and low viscosity dimers:

TABLE 1 Formulation of the high silicone content curing agent MoleWeight Factor Actual A Si-Dimers 734.3 1 734.3 ⅙ 122.4 B DMAPA 102.184.2 429.2 ⅙ 71.5 C Paraformaldehyde 30 4.2 138.6 ⅙ 23.1 91% DAminopropyl- 25000 0.033 824.7 ⅙ 137.45 siloxaneThe Si-dimers (component A) may be either the high viscosity dimer ofexample 3 or the low viscosity dimer of example 4 above. Components A,B, C and D are combined in the proportions set forth in Table 1 in areactor equipped with agitation, thermocouple temperature control, andcondenser. For this example, a 500 ml four neck flask was used. Afterthe components are combined, the temperature is raised to about 75° C.and held for 4 hours. Vaccuum distillation is used at about 75° C. and10 mm Hg to remove water. The resulting curing agent has the propertieslisted in Table 2 using either a low viscosity dimer or a high viscositydimer.

TABLE 2 Analytical results for the high silicone content curing agentsfrom low and high viscosity dimers From the low viscosity From the highviscosity LX-5335 dimers dimers Visc@25 10240 16850 Amine value 200 190V. Loss 3.5 2.3 Gel time 59.1 50.8

EXAMPLE 6 Epoxy Resin Made from the Low and High Viscosity Dimers

The following reagents are used in the amounts shown to synthesize theepoxy from the high and low viscosity dimers:

TABLE 3 Formulation for the synthesis of epoxy resin from the siliconedimer FW Ratio Weight Factor Final Charge A Si-dimers 734.3 1 734.30.2043 150 B Epichlorohydrin 92.5 7.6 703 0.2043 144 C IPA 60 9.47 5680.2043 95 D DI water 18 6.4 115 0.2043 25 E NaOH (50%) 40 3 240 0.204349 F DI water 18 38.76 698 0.2043 143

The Si-dimers (component A) may be either the high viscosity dimer ofexample 3 or the low viscosity dimer of example 4 above. Components A,B, C and D are combined in the proportions set forth in Table 1 in areactor equipped with agitation, thermocouple temperature control, afunnel and a condenser. For this example, a 1 liter four neck flask wasused. After components A, B, C and D are added to the flask, they aremixed for about 20 minutes. The caustic is then added slowly to theflask through the funnel over a period of about 30 minutes. Temperatureis controlled below 65° C. using a cooling water bath.

After the caustic is added, the temperature is held at 65° C. for about4 hours. The DI water is then added through the addition funnel, and thecontents of the flask are held at 65° C. and agitated for 30 minutes.The solution is transferred from the flask to a separation funnel andallowed to separate until there are clear aqueous and organic layers.This takes about 30 minutes in the laboratory. After separation, thebottom aqueous layer is drained.

The top organic layer is transferred to a clean flask. Excess solventand free epichlorohydrin is removed by vacuum distillation at about 125°C. at 5 mm Hg. The resulting epoxy product has the followingcharacteristics:

TABLE 4 Analytical results for the silicone dimers From the HighViscosity From the Low viscosity LX-5333 Dimers dimers Visc@25 1400 370EEW 524 502 V. Loss 1.3 0.4 Hydrolizable Cl % 0.3 0.8

EXAMPLE 7 Process for Production of Silicone Dimer Based FrictionParticles

Friction particles may be made using any of the silicone cardanol dimersdiscussed above. In this Example, friction particles were made usingcardanol dimers prepared by the method of Example 1 above with n=1. Theparticles may be made by blending about 50 grams of silicone dimers with5 grams of hexamethylene tetramine in an appropriate container. Themixture is cured in an over at 180° C. for about 4 hours. The materialis cooled to room temperature, broken into small pieces and ground intoa fine powder. Friction particles prepared in this manner may have thefollowing properties.

TABLE 5 Analytical properties of the Si-dimers based friction particles.From high visc From low visc Brown Particles Si-dimer Si-dimer Acetoneextraction 1.3 0.3 370 C. V. Loss 15.8 16.2 Acetone Extraction 2.6 2.9After 370 C. V. Loss pH 7.35 6.78 Ash 1.6 1.7

EXAMPLE 8 Novolacs Phenolic Resins from Silicone Dimers

The following reagents were used in the amounts shown to produce aphenolic resin from the long chain silicone cardanol dimers describedabove. In this example, long chain silicone dimers with n=5 were used.The materials used to prepare the phenolic resin were as follows:

Moles Actual Description MW Ratio Mass Factor charge A Si-Dimers 734 1734 0.1635  120 g B Paraformaldehyde 33 0.75 24.75 0.1635 4.04 g COxalic Acid 90.03 0.01359 1.223 0.1635  0.2 g

In this example, 120 g of the Si dimer was combined in a 500 ml flaskwith 4.04 g of paraformaldehyde and mixed for about 20 minutes. Oxalicacid was then added to the flask and the temperature increased to 90°C.-100° C. and held at temperature for about 4 hours. The mixture wasthen cooled to room temperature. The phenolic resin produced by thisprocess had a viscosity at 25° C. of about 2560 cP.

It should be understood that the results provided in these examples arefor the products produced in the manner described, and that theseresults are not intended to limit the scope of the invention in any way,and they are exemplary only. While specific embodiments of the presentinvention have been described above, one skilled in the art willrecognize that numerous variations or changes may be made to theinvention described above without departing from the scope of theinvention as recited in the appended claims. Accordingly, the foregoingdetailed description of specific embodiments of the invention isintended to describe the invention in an exemplary, rather than alimiting, sense.

1. A compound for use as a curing agent for an epoxy having a formulaselected from the group consisting of:

wherein x is 9, 13, 33 or
 66. 2. A process for producing a cardanolbased epoxy curing agent comprising the steps of: (a) combining cardanoland acetic anhydride in a reactor and maintaining the reactor at atemperature of between about 120° C. to 125° C. for a period of betweenabout 3 and 4 hours; (b) combining the reaction product from step (a)with dimethylmethoxysilane and a catalyst in a reactor and maintainingthe temperature at between about 120° C. and about 160° C. for a periodof about 20 hours; (c) hydrolizing the reaction product from step (b)with an acid wash solution to produce a silane substituted cardanol; (d)combining the product from step (c) with paraformaldehyde and1,3-Bis(3-aminopropyl) polydimethylsiloxane in a reactor and maintainingthe reactor at a temperature of between about 70° C. to about 80° C. fora period of between about 4 and about 6 hours.
 3. The process of claim2, wherein the 1,3-Bis(3-aminopropyl) polydimethylsiloxane has 9, 13, 33or 66 dimethylsiloxane units.
 4. A process for producing a cardanolbased epoxy curing agent comprising the steps of: (a) combining cardanoland acetic anhydride in a reactor and maintaining the reactor at atemperature of between about 120° C. to 125° C. for a period of betweenabout 3 and 4 hours; (b) combining the reaction product from step (a)with (Tridecafluoro-1,1,2,2-Tetrahydrooctyl)silane and a catalyst in areactor and maintaining the temperature at between about 120° C. andabout 160° C. for a period of about 20 hours; (c) hydrolyzing thereaction product from step (b) with an acid solution to produce afluorosilane substituted cardanol; (d) combining the product from step(c) with paraformaldehyde and 1,3-Bis(3-aminopropyl)polydimethylsiloxane in a reactor and maintaining the reactor at atemperature of between about 70° C. to about 80° C. for a period ofbetween about 4 and about 6 hours.
 5. The process of claim 4, whereinthe 1,3-Bis(3-aminopropyl)polydimethylsiloxane has 9, 13, 33 or 66dimethylsiloxane units.